Blippy.scala

sealed trait Thingy[+A] {
  def bla(x: String): String
  val bla2: String ⇒ String = bla
}
case class Good[A](x: A) extends Thingy[A] { def bla(x: String) = x }
case class Bad(t: String) extends Thingy[Nothing] { def bla(x: String) = t }

object Thingy {
  def good1[A](x: A): Thingy[A] = Good(x)

  def good2[A]: A => Thingy[A] = _good.asInstanceOf[A => Thingy[A]]


  def bad1(t: String): Thingy[Nothing] = Bad(t)

  val bad2: String => Thingy[Nothing] = Bad.apply


  private[this] val _good: Any => Thingy[Any] = Good.apply
}

// <name>8 variants are possible 2.12. bytecode, generated with
// -cp ~/.ivy2/cache/org.scala-lang.modules/scala-java8-compat_2.11/bundles/scala-java8-compat_2.11-0.7.0.jar:. 
// -target:jvm-1.8
// -Xexperimental
// -Ydelambdafy:method
// -Ybackend:GenBCode
object Blippy {

  def main(args: Array[String]): Unit = {

    //  0: getstatic     #19                 // Field Thingy$.MODULE$:LThingy$;
    //  3: bipush        42
    //  5: invokestatic  #25                 // Method scala/runtime/BoxesRunTime.boxToInteger:(I)Ljava/lang/Integer;
    //  8: invokevirtual #29                 // Method Thingy$.good1:(Ljava/lang/Object;)LThingy;
    // 11: astore_2
    val a = Thingy.good1(42)

    //  0: getstatic     #26                 // Field Thingy$.MODULE$:LThingy$;
    //  3: bipush        42
    //  5: invokestatic  #32                 // Method scala/runtime/BoxesRunTime.boxToInteger:(I)Ljava/lang/Integer;
    //  8: invokevirtual #36                 // Method Thingy$.good1:(Ljava/lang/Object;)LThingy;
    // 11: astore_2
    val a8 = Thingy.good1(42)



    // 12: getstatic     #19                 // Field Thingy$.MODULE$:LThingy$;
    // 15: invokevirtual #33                 // Method Thingy$.good2:()Lscala/Function1;
    // 18: bipush        42
    // 20: invokestatic  #25                 // Method scala/runtime/BoxesRunTime.boxToInteger:(I)Ljava/lang/Integer;
    // 23: invokeinterface #39,  2           // InterfaceMethod scala/Function1.apply:(Ljava/lang/Object;)Ljava/lang/Object;
    // 28: checkcast     #41                 // class Thingy
    // 31: astore_3
    val b = Thingy.good2(42)

    // 12: getstatic     #26                 // Field Thingy$.MODULE$:LThingy$;
    // 15: invokevirtual #40                 // Method Thingy$.good2:()Lscala/Function1;
    // 18: bipush        42
    // 20: invokestatic  #32                 // Method scala/runtime/BoxesRunTime.boxToInteger:(I)Ljava/lang/Integer;
    // 23: invokeinterface #46,  2           // InterfaceMethod scala/Function1.apply:(Ljava/lang/Object;)Ljava/lang/Object;
    // 28: checkcast     #48                 // class Thingy
    // 31: astore_3
    val b8 = Thingy.good2(42)



    // 32: getstatic     #19                 // Field Thingy$.MODULE$:LThingy$;
    // 35: ldc           #43                 // String 1337
    // 37: invokevirtual #47                 // Method Thingy$.bad1:(Ljava/lang/String;)LThingy;
    // 40: astore        4
    val c = Thingy.bad1("1337")

    // 32: getstatic     #26                 // Field Thingy$.MODULE$:LThingy$;
    // 35: ldc           #50                 // String 1337
    // 37: invokevirtual #54                 // Method Thingy$.bad1:(Ljava/lang/String;)LThingy;
    // 40: astore        4
    val c8 = Thingy.bad1("1337")



    // 42: getstatic     #19                 // Field Thingy$.MODULE$:LThingy$;
    // 45: invokevirtual #50                 // Method Thingy$.bad2:()Lscala/Function1;
    // 48: ldc           #43                 // String 1337
    // 50: invokeinterface #39,  2           // InterfaceMethod scala/Function1.apply:(Ljava/lang/Object;)Ljava/lang/Object;
    // 55: checkcast     #41                 // class Thingy
    // 58: astore        5
    val d = Thingy.bad2("1337")

    // 42: getstatic     #26                 // Field Thingy$.MODULE$:LThingy$;
    // 45: invokevirtual #57                 // Method Thingy$.bad2:()Lscala/Function1;
    // 48: ldc           #50                 // String 1337
    // 50: invokeinterface #46,  2           // InterfaceMethod scala/Function1.apply:(Ljava/lang/Object;)Ljava/lang/Object;
    // 55: checkcast     #48                 // class Thingy
    // 58: astore        5
    val d8 = Thingy.bad2("1337")



    // 60: new           #52                 // class Blippy$$anonfun$4
    // 63: dup
    // 64: invokespecial #53                 // Method Blippy$$anonfun$4."<init>":()V
    // 67: new           #55                 // class Blippy$$anonfun$5
    // 70: dup
    // 71: invokespecial #56                 // Method Blippy$$anonfun$5."<init>":()V
    // 74: invokeinterface #60,  2           // InterfaceMethod scala/Function1.andThen:(Lscala/Function1;)Lscala/Function1;
    // 79: bipush        42
    // 81: invokestatic  #25                 // Method scala/runtime/BoxesRunTime.boxToInteger:(I)Ljava/lang/Integer;
    // 84: invokeinterface #39,  2           // InterfaceMethod scala/Function1.apply:(Ljava/lang/Object;)Ljava/lang/Object;
    // 89: checkcast     #62                 // class java/lang/String
    // 92: astore        6
    val e = (Thingy.good1[Int] _).andThen(_.bla("Bernd"))(42)

    // 60: invokedynamic #78,  0             // InvokeDynamic #0:apply:()Lscala/compat/java8/JFunction1;
    // 65: invokedynamic #85,  0             // InvokeDynamic #1:apply:()Lscala/compat/java8/JFunction1;
    // 70: checkcast     #42                 // class scala/Function1
    // 73: invokeinterface #89,  2           // InterfaceMethod scala/Function1.andThen:(Lscala/Function1;)Lscala/Function1;
    // 78: bipush        42
    // 80: invokestatic  #32                 // Method scala/runtime/BoxesRunTime.boxToInteger:(I)Ljava/lang/Integer;
    // 83: invokeinterface #46,  2           // InterfaceMethod scala/Function1.apply:(Ljava/lang/Object;)Ljava/lang/Object;
    // 88: checkcast     #91                 // class java/lang/String
    // 91: astore        6
    val e8 = (Thingy.good1[Int] _).andThen(_.bla("Bernd"))(42)
 


    //  94: getstatic     #19                 // Field Thingy$.MODULE$:LThingy$;
    //  97: invokevirtual #33                 // Method Thingy$.good2:()Lscala/Function1;
    // 100: new           #64                 // class Blippy$$anonfun$6
    // 103: dup
    // 104: invokespecial #65                 // Method Blippy$$anonfun$6."<init>":()V
    // 107: invokeinterface #60,  2           // InterfaceMethod scala/Function1.andThen:(Lscala/Function1;)Lscala/Function1;
    // 112: bipush        42
    // 114: invokestatic  #25                 // Method scala/runtime/BoxesRunTime.boxToInteger:(I)Ljava/lang/Integer;
    // 117: invokeinterface #39,  2           // InterfaceMethod scala/Function1.apply:(Ljava/lang/Object;)Ljava/lang/Object;
    // 122: checkcast     #35                 // class scala/Function1
    // 125: ldc           #67                 // String Bernd
    // 127: invokeinterface #39,  2           // InterfaceMethod scala/Function1.apply:(Ljava/lang/Object;)Ljava/lang/Object;
    // 132: checkcast     #62                 // class java/lang/String
    // 135: astore        7
    val f = Thingy.good2[Int].andThen(_.bla2)(42)("Bernd")

    //  93: getstatic     #26                 // Field Thingy$.MODULE$:LThingy$;
    //  96: invokevirtual #40                 // Method Thingy$.good2:()Lscala/Function1;
    //  99: invokedynamic #98,  0             // InvokeDynamic #2:apply:()Lscala/compat/java8/JFunction1;
    // 104: checkcast     #42                 // class scala/Function1
    // 107: invokeinterface #89,  2           // InterfaceMethod scala/Function1.andThen:(Lscala/Function1;)Lscala/Function1;
    // 112: bipush        42
    // 114: invokestatic  #32                 // Method scala/runtime/BoxesRunTime.boxToInteger:(I)Ljava/lang/Integer;
    // 117: invokeinterface #46,  2           // InterfaceMethod scala/Function1.apply:(Ljava/lang/Object;)Ljava/lang/Object;
    // 122: checkcast     #42                 // class scala/Function1
    // 125: ldc           #100                // String Bernd
    // 127: invokeinterface #46,  2           // InterfaceMethod scala/Function1.apply:(Ljava/lang/Object;)Ljava/lang/Object;
    // 132: checkcast     #91                 // class java/lang/String
    // 135: astore        7
    val f8 = Thingy.good2[Int].andThen(_.bla2)(42)("Bernd")
  }
}